Influence of temperature and magnetic field on phosphorescence from Ir(ppy)3

The basic features of phosphorescent emission from Ir(ppy)3 (ppy=2-phenylpyridinate), dissolved in THF, were investigated by a magneto-luminescence technique. It is found that there are two peaks in the phosphorescent spectra in visible region from 2.2~77 K. They are located at 547.70 nm and 515.70 nm wavelength. This is due to radiative electronic transition from two substates in 3MLCT structure to the ground state of Ir(ppy)3. Changing temperature can vary electron distribution and life-time on different substates in the 3MLCT structure of Ir(ppy)3. Thus, we can observe a strong dependence of the phosphorescent spectrum on temperature. Furthermore, we find that the intensity of phosphorescent emission from Ir(ppy)3 increases with magnetic field at 2.2 K. The presence of the high magnetic field can alter the electronic states and, thus, modulate the electron distribution and transition possibility for substates in 3MLCT. As a result, the phosphorescence emission from Ir(ppy)3 can be enhanced by the presence of the magnetic field. © 2015, Science Press. All right reserved.